Isolation And Identification Of Psychrophilic Phosphorus Accumulating Bacteria And The Study Of Their Phosphorus Accumulating Characteristics

At present,eutrophication is a common water pollution problem.Phosphorus is the limiting factor of eutrophication,so phosphorus removal is one of the keys to solve the problem of eutrophication.The biological phosphorus removal method based on phosphate-accumulating organisms?PAOs?has become the most widely used phosphorus removal technology due to its safe and efficient performance.Most studies on PAOs focus on medium temperature area,but there are few studies on psychrophilic phosphate-accumulating organisms,the research on psychrophilic PAOs faces the problems of less species and low efficiency of phosphorus uptake.The purpose of this experiment was to screen out efficient psychrophilic PAOs applied in low temperature environment.The phosphorus accumulation characteristics of the strains were studied under low temperature?15??,including growth trend,phosphorus uptake characteristics,phosphorus uptake capacity,optimization of phosphorus uptake conditions and immobilization.1.In shandong yantai fushan district tower mountain cave silt samples,first by enrichment and scribing culture isolate strains;And then use the blue white spot early screening method to screen strains which have the capacity of phosphorus uptake;The next step was to screen the strains with strong P-uptake capacity through the rescreening method of cohesion staining;Finally through the determination of 15?under the condition of P-uptake rate taken quantitative various strains of psychrophilic P-uptake capability,selection of P-uptake rate more than 80%of5 strains of organisms as a follow-up experiment object.The methods of 16S rDNA molecular identification,morphological observation and physiological and biochemical characteristics test were used to identify the selected strains.A39 is Acinetobacter strain,B12 is Raoultella strain and C8 is Pseudomonas strain.2.Three strains under the condition of low temperature?15??,were determined their characteristics of growth trend and phosphorus-uptake:When the three strains were cultured in low-temperature phosphorus accumulating medium,the change trend of phosphorus content in the supernatant with the culture time were measured.Taking the experimental group with an initial phosphorus concentration of 5 mg/L as an example,it was found that the P-uptake trend of the three strains was first rapid uptake and then slow release.Therefore,the removal of phosphorus in water by various strains are not that the longer time it takes,the better the effect are;Three kinds of bacteria were cultured at different initial concentrations for 24 hours,and the results of phosphorus uptake rate,P-uptake content and the phosphorus content in the bacteria were compared,the results show that P-uptake capacity in comparison:A39>B12>C8.The P-uptake capacity of A39 strain is very outstanding,the phosphorus content of its bacteria was8.87%,and the phosphorus uptake rate reached 99.43%,96.26%and 67.44%,at the same tiem,the P-uptake content reached 1.989 g,4.813 g and 6.744 g,respectively,at the initial phosphorus concentration of 2,5 and 10 mg/L.3.The P-uptake capacity of strain A39 was optimized by single factor and response surface methodology:By optimizing the single factor conditions of five factors and combining with the software Minitab 17 factor significance analysis,it is concluded that pH,temperature and inoculation volume have significant relationship with the change of P-uptake rate.The response surface method was designed by using three factors of pH,temperature and inoculation volume,and implemented by BBD.Based on the analysis of the experimental data and the actual situation,the optimum phosphorus uptake conditions were determined for strain A39 at pH 6.0,temperature 15?and inoculation volume 4%.It was verified that the phosphorus uptake rate reached 71.99%.The reliability of the response surface experiment results was high.4.The relation of antagonistic effects among A39,B12 and C8 strains were determined by the Oxford cup method,the result was not-significant.By comparing the phosphorus uptake rates of the three strains in different proportion,the results showed that the best phosphorus uptake rate was 73.69%when the ratio of A39:B12:C8 was 2:1:1.5.Microbial immobilized pellets by embedding and co-adsorbing method were prepared using PVA-SA as the embedding carrier,GODQs-magnetic chitosan oligosaccharide solution as the adsorbent,and CaCl₂/saturated boric acid solution as the crosslinking agent,compound organisms as immobilized microorganisms.Through L₉?3⁴?orthogonal experiment,the optimal preparation ratio of immobilized pellets of high-efficient cryophilus composite bacteria was obtained:every 100 mL system contained 6 g PVA,2 g SA,18 mL magnetic chitosan oligosaccharide solution 2 g GOQDs and 5 g of composite bacteria wet bacteria,and the crosslinking agent was 3%calcium chloride/saturated boric acid solution.The immobilized pellets are manufactured that embedded with compound PAOs with high efficiency of phosphorus-uptake.Measure its performance that:?1?the immobilized pellets were cultured in a conical flask shaker for 15 days,and it was found that the damage rate of the immobilized pellets was 6%,which proved that the immobilized pellets had high strength and could be used for many times;?2?the phosphorus uptake rate of the immobilized pellets cultured in 10 mg/L polyphosphate medium for 24 h was 75.6%,which was partially improved 1.91%compared with the phosphorus uptake rate of composite bacteria under the same conditions.6.The immobilized pellets embedded with compound PAOs are used to study the phosphorus uptake in aquaculture water at 15?.When the TP concentration was 0.765 mg/L in the culture water for 30 hours,phosphorus-uptake rate was 77.92%,the water content of TP was0.169mg/L,effluent live up to?class water quality standards;At the same time,when the TP concentration was 8.26 mg/L in the culture water for 3 days,the phosphorus uptake rate was only42.43%.Therefore,in practical application,the immobilized product prepared by this experiment alone is suitable for the treatment of low-phosphorus sewage at low temperature.